Multiple-pillar elastomeric resonator

ABSTRACT

A device for radiating elastic pressure pulses into a liquid container which comprises a tank for containing a liquid therein having an orbiting mass oscillator coupled outside the bottom surface of the tank and a plurality of elastomeric pillar elements affixed to the bottom surface of the tank extending within the tank about its circumference.

United States Patent inventor Albert G. Bodine 3,410,534 11/1968 Wyczalek 259/72 7877 Woodley Ave., Van Nuys, Calil. 3,417,630 12/ l 968 Bruder1ein.... 74/61 App]. No. 833,294 3,516,645 6/1970 Arndt 259/72 Filed June 16, 1969 2,498,990 2/1950 Fryklund.. 259/72 Patented Dec. 7,1971 2,815,193 12/1957 Brown 259/72 Continuation-impart of application Ser. No. 3,096,080 7/ 1963 Wi1lems... 259/ 1 666,398, Sept. 8, 1967, now Patent No. 3,151,846 10/1964 George 259/1 UX 3,544,073. This application June 16, 1969, 3,299,722 1/1967 Bodine, Jr. 259/1 X Ser. No. 833,294 3,410,765 l2/1968 Bodine 259/1 X OTHER REFERENCES MULTIPLE-PILLAR ELASTOMERIC RESONATOR 1,036,602 8-1958 German Application (WENK) 134- l84 9 Claims, 3 ng 3 Primary Examiner-James Kee Chi u.s. Cl 259/72, m

259/ 1, 74/61 lnt.Cl iggillllllzii ABSTRACT: A device for radiating elastic pressure pulses Field of Search 259/72 into a liquid container which comprises a tank for containing a liquid therein having an orbiting mass oscillator coupled out- 74,6187 173/49 175/55 l34/l84 side the bottom surface of the tank and a plurality of CM rr i'i i air"; 2:333:32? UNITED STATES PATENTS e ex n e a 2,960,314 11/1960 B0dine,.lr. 259/1 X 11, T 27 2l- 37 25 l 2 2 l9 PATENTEU mm mm 3625486 INVENTOR.

A LBERT G. BOD/NE BY SOKOLSKI 8 WOHLGEMUTH MULTIPLE-PILLAR ELASTOMERIC RESONATOR This is a continuation-in-part of application Ser. No. 666,398, filed Sept. 8, 1967 now U.S. Pat. No. 3,544,073.

In the previous filed patent application Ser. No. 666,398 filed Sept. 8, 1967 by the same inventor, there is disclosed a device which is comprised of an elastomeric resonator cou pled to an orbiting mass oscillator. The elastomeric resonator is disclosed as being a tubular element having one end connected to an orbiting mass oscillator, with the other end extending into a tank of water or other suitable fluid. Articles of fluids to be cleaned or treated are then submerged in or a part of the liquid bath, the desired action benefiting from the sonic resonant energy delivered thereto. in the embodiments disclosed in the prior filed application, the tubular resonator element extends only partially with the bottom surface of the fluid containing tank, with the liquid filling the inner cavity of the resonator and sealing means provided about its outer circumference to prevent leakage between the tank and the outer walls of the tubular element. In the prior case, the resonator element alone was vibrated; and precaution had to be taken to prevent leakage of the fluid about it into the surrounding environment.

Thus, an object of this invention is to provide a novel elastomeric resonator combination which will involve improved coupling of the resonator to a liquid body.

The above and other objects of this invention are accomplished by the herein device which comprises a vessel or tank for containing a liquid medium which could be utilized to clean parts or cause general sonic treatment and the like. The bottom of the tank is preferably a separate element and is connected to the sidewall of the tank through a suitable gasket to prevent leakage of fluid. Mounted outside of the bottom of the tank and coupled thereto is an orbiting mass oscillator which causes the bottom of the tank to resonantly vibrate. Affixed to the inside surface of the bottom of the tank are a plurality of individual separate pillars of elastomeric material such as rubber, which extend upwardly in said tank about its inner circumference. In one embodiment each pillar is a section of a hollow cylinder, while in another embodiment each pillar comprises an individual cylindrical element. In a further embodiment of the invention, top surfaces of the pillars, opposite to the end connected to the bottom of the tank, have a heavy metal mass affixed thereto in order to better counterbalance the mass of the tank.

It is believed the invention will be better understood from the following detailed description and drawings, in which:

FIG. 1 is a partially sectioned side view of the device of this invention;

FIG. 2 is a sectional view taken along lines 2-2 of FIG. 1;

F IG. 3 is a sectional view ofa second embodiment of this invention disclosing cylindrical elastomeric pillar elements.

It is helpful to the comprehension of this invention to make an analogy between a mechanical resonant circuit and an electrical resonant circuit. This type of analogy is well known to those skilled in the art and is described, for example, in chapter 2 of Sonics" by Hueter and Bolt, published in 1955 by John Wiley and Sons. in making such an analogy, force F is equated with electrical voltage E, velocity of vibration u is equated with electrical current i, mechanical compliance C,,, is equated with electrical capacitance C,., means M is equated with electrical inductance L, mechanical resistance (friction) R,, is equated with electrical resistance R, and mechanical impedance Z,,, is equated with electrical impedance 2,. Thus, it can be shown that if a member is elastically vibrated by a sinusoidal force, F sinmt, to being equal to 21: times the frequency of vibration, that 2 -R +](wM u 7 (1) Where wM is equal to l/wC,,,, a resonant condition exists,

and the effective mechanical impedance Z,, is equal to the mechanical resistance R,,,, the reactive impedance components mM and l/wC cancelling each other out. Under such a resonant condition, velocity of vibration u is at a maximum, effective power factor is near unity, and energy is efficiently delivered to the object being vibrated. It is such a high-efficiency resonant condition in the elastic system being driven that is preferably utilized in the methods and devices of this invention to achieve the desired end results.

It is to be noted by reference to equation l that velocity of vibration u is highest where impedance Z, is lowest, and vice versa. Therefore, a high-impedance load will tend to vibrate a relatively low velocity, and vice versa. Thus, at an interface between highand low-impedance elements, a high relative movement results by virtue of such impedance mismatch which, as in the equivalent electrical circuit, results in a high reflected wave. Where a low-impedance load, such as water, is present, the acoustic impedance of the elastomer so closely matches that maximum transfer of the vibratory energy is achieved. A mismatch of impedance arises at the interface of the water and parts submerged therein, for example, wherein a desired cleaning action can occur.

Just as the sharpness of resonance of an electrical circuit is defined at the 0" thereof, and is indicative of the ratio of energy stored to the energy used in each cycle, so also the 0" of a mechanical resonant circuit has the same significance and is equal to the ratio between wM and R,,,. Thus, high efficiency and considerable cyclic motion can be achieved by designing the mechanical resonant circuit for high Q.

Of particular significance in the implementation of the methods and devices of this invention is the high acceleration of the components of the elastic resonant system that can be achieved at sonic frequencies. It can be shown that the acceleration of a vibrating mass is a function of the square of the frequency of the drive signal times the amplitude of vibration. Under resonant conditions, the amplitude of vibration is at maximum and thus even at moderately high sonic frequencies very high accelerations are achieved.

In considering equation l several factors are to be noted. First, this equation represents the total effective resistance, mass and compliance in a vibrating circuit, and these parameters are generally distributed throughout the system rather than being lumped in any one component or portion thereof. Secondly, the vibrating system often includes surrounding components, a container holding the water and the water itself.

It is also to be noted that orbiting mass oscillators are utilized in the devices of the invention that automatically adjust their output frequencies to maintain resonance with changes in the characteristics of the load. Thus, in situations where we are dealing with parts which are placed in a bath during the operation of the device which will change that load, the system automatically is maintained in optimum resonant operation by virtue of the lock-in" characteristics of applicant's orbiting mass oscillators. The vibrational outputs from such orbiting mass oscillators are generated along a controlled predetermined coherent path to provide maximum output along a desired axis or axes. The orbiting mass oscillator automatically changes not only its frequency but its phase angle and therefore its power factor with changes in the resistive impedance load to assure optimum efficiency of operation at all times. Such orbiting mass oscillators are capable of efficiently generating high-level vibrational outputs.

By utilizing as a resonator element an elastomeric material such as rubber, a much greater feedback to the oscillator is accomplished than when the resonator is of a high-impedance material such as, for example, a steel column. This feedback results, since the elastomer, because of its inherently low impedance, provides a greater cyclic stroke for a given frequency at the point where the oscillator is connected. Previously, other low-impedance resonator elements such as air springs have been affixed to an oscillator. However, these elements have lumped constant impedance characteristics. On the other hand, the elastomeric material is a distributed constant system. A distributed constant system has the advantage of being able to accomplish an acoustic lever effect where, for

example. a high velocity or amplitude vibration at the interface of the oscillator can be converted to a low velocity with a high force at the end of the resonator exposed to the load element.

Further, as indicated, one of the advantages of an orbiting mass oscillator is its lock-in characteristic, with the automatic adjustment of operating frequencies to accommodate for sudden changes in environmental reactive impedance. This feedback is best accomplished by a low-impedance resonator, such as the elastomeric element disclosed which has a large-amplitude vibration to better accomplish the feedback. Additionally, in this same vein, the automatic accommodation for changes in environmental resistive impedance caused by a work load is better fed back to the oscillator through a low-impedance resonator since there is greater activity where the resonator is coupled.

Turning now to FIGS. 1 and 2, there is seen the device of this invention which comprises a vessel or tank 11 having a cylindrical sidewall. A separate top or lid 13 is provided and clamped by clamps 15 to an upper flange 17 formed on the tank 11. The top 13 is removable so that the liquid, such as water, oil, chemicals or the like, can be admitted to the tank for treatment, or together with pans of material to be cleaned or otherwise treated therein. Top 13 can be, for example, a clear plastic material such that one can view the action that transpires within the tank.

The bottom end of the tank 11 is provided with an outward flange portion 19 to which is secured a baseplate 21 by bolts 23. Additionally, an exit drain line 25 is located in the walls of the tank 11 adjacent the flange portion 19. The base 21 is preferably provided with an inward extending centered dome portion 27 which serves as a main vibratory radiating surface. It is to be noted that between the base 21 and the flange portion 19 there is a gasket 29 that serves to prevent leakage of the fluid in the tank between the wall 11 and the base 21 at the flange portion. Afiixed to the base plate 21 is a mounting bracket 31 which secures an orbiting mass oscillator 33 of the type disclosed in US. Pat. No. 3,402,6l2. The oscillator can be driven by a shaft from a motor not shown. Thus, output from the oscillator 33 is carried by the bracket 31 to the baseplate 21 such that it can radiate into the liquid within tank 11.

Afi'lxed to baseplate 21 and extending upwardly therefrom within the tank 11 are a plurality of elastomeric pillars 35 which may be of rubber or rubberlike material. The pillars 35 preferably have steel inserts 37 integrally imbedded in their base portion so that they can be attached by bolts 39 to the bottom plate 21 and mounting bracket 31 as seen in FIG. 1. In this embodiment, separate metal plates 41 are shown fixed to the top of the pillars by adhesive or the like, and serve to add additional mass to the elastic elements.

The device of the invention can be supported on a structure 43 formed of welded angle iron. As seen in FIGS. land 2, four equidistantly spaced legs 45 extend from the ground upwardly. The legs further support a ring element 47 that has a rubber cushion 49 affixed thereto. The ring 47 serves as a guard, and its stiffness prevents undue wall motion of the tank 11 during vibration. The four corners of the support structure 43 located below the bottom 21 of the tank are four plates 51. Seated on top of the plates 51 are four isolators 53 which are formed of rubber. The isolators are connected to the plate 51 and the bottom 21 of the tank. The isolators may be of rubber or similar material and serve to isolate the support structure 43 from the vibrator energy imparted to the remaining portion of the device. The isolators are affixed to the bottom of the tank through four tabular extensions 55, seen in FIG. 2, that are integrally connected on both the bottom surface 21 of the tank and the corresponding isolator mounting plate 31 by bolts 57.

In the operation of the device, the tank 11 functions as one opposed mass, while the mass particularly in the upper portions of the elastomeric pillars 35 functions as the other opposed vibratory mass. Thus, when the oscillator vibrates the bottom surface 21 of the tank and moves it upward, a positive pressure is generated in the liquid. At the same time, the elastomeric column 35 is compressed or moving in a downward position and becoming thicker, also generating a positive pressure pulse in the liquid. Thus, the tank bottom 21 and elastomeric pillars 35 function cooperatively to exert simultaneous pressure pulses on the liquid in the tank. Thus, it can be appreciated that since the elastomeric pillars function to counterbalance the mass of the tank, there is provided a unitary resonant structural combination wherein no counterbalancing forces are further needed to cause the tank 11 to vibrate.

The elastomeric pillars are clustered close together as seen particularly in FIG. 2, and also located in close proximity to the outer tank wall, so that the liquid is maintained in a film in the space 59 circumferentially surrounding the pillar elements. This tends to discourage unwanted lateral bending modes in the pillars. In other words, functioning in this environment the pillars tend to stay more in a longitudinal mode.

It should be pointed out that the elastomeric pillars may be provided with an oil resistant coating so that a wider range of liquids can be treated. This coating can be a vulcanized layer of an oil resistant material or some other high polymeric material. The coatings can also be vulcanized or glued directly onto the pillar elements.

The gasket 29 located at the bottom of the tank effects the vibration of the bottom plate 21. If the gasket is quite thick, most of the vibration will be confined to the bottom plate with the sidewalls of the tank moving very little. In other words, the resiliency of the gasket will take up much of the motion of the walls of the tank. However, a thick gasket is not required if the sidewall is made of very thin material, such as thin stainless steel, so that the total mass of the tank is kept to a minimum where the elastomeric pillars are not of a massive construction. It is in relation to the mass problem that the plates 41 are affixed to the pillars 35. Where the mass of the tank is substantial as compared to the pillars, the plates are preferred to counterbalance the tank mass. However, in many instances the mass of the tank can be counterbalanced sufficiently without the utilization of such plates 41.

Turning to FIG. 3, there is seen the employment of a less precise shape or cross section of pillar elements 61. As can be seen, in a cluster of round pillars 61, they approach each other in the outer wall 63 ofa tank only along a vertical line rather than an extended surface as seen in the embodiments of FIGS. 1 and 2. The round pillars do not have as much effective liquid layer damping as is available with the shaped pillars, but in several situations this line contact is sufiicient to prevent serious lateral bending vibration of the pillars.

During the operation of the device of this invention, the orbiting mass oscillator 33 is adjusted so that it has a frequency just below that for peak resonant amplitude. This frequency selection gives stability so that the oscillator stays locked in" to resonant as the load impedance'changes within the tank. The load impedance will change, such as due to release of gas in the liquid, particularly in a case where chemical reactions are taking place. Another factor which affects the load impedance is the insertion of a basket of parts into the liquid which parts are to be cleaned by liquid cavitation. The placement ofsuch parts will greatly change the resistive impedance. This, however, is another important advantage of the orbiting mass oscillator in that it changes its phase angle to accommodate for changes in resistive impedance.

Thus, it can be seen that in the operation of the orbiting mass oscillator of the device, resonance is set up within the system whereby the tank bottom 21 vibrates vertically so as to present an acoustic wave radiating effect into the liquid in the tank. At the same time, the counteracting resonant vibration of the multiple pillars also acts to generate similarly phased pressure wave fluctuations in the liquid. The result is that the confined body of liquid, particularly within the center of the circle of pillars, is subjected to high-energy elastic vibration to achieve cavitation of the liquid.

lclaim:

1. In combination:

a radiating member,

an orbiting mass oscillator coupled to one side of said member,

a plurality of individual elastomeric resonator elements affixed to and extending from the opposite side of said member,

a liquid bath surrounding said plurality of elements, and

means for driving said oscillator at a frequency such as to cause resonant vibration of said member and said elements.

2. The combination of claim 1 and further comprising:

a tank for containing a liquid,

said member being affixed to said tank to enclose the bottom thereof with said elastomeric elements extending within said tank.

3. The combination of claim 2, wherein said tank has a circular cross section, and said elements are disposed about the inner periphery of said tank.

includes a resilient cushion spatially disposed from and surrounding a section of an outer wall portion of said tank.

9. The combination of claim 1 further comprising: a mass attached to an end of the element opposite the end affixed to said radiating member.

l l t I 

1. In combination: a radiating member, an orbiting mass oscillator coupled to one side of said member, a plurality of individual elastomeric resonator elements affixed to and extending from the opposite side of said member, a liquid bath surrounding said plurality of elements, and means for driving said oscillator at a frequency such as to cause resonant vibration of said member and said elements.
 2. The combination of claim 1 and further comprising: a tank for containing a liquid, said member being affixed to said tank to enclose the bottom thereof with said elastomeric elements extending within said tank.
 3. The combination of claim 2, wherein said tank has a circular cross section, and said elements are disposed about the inner periphery of said tank.
 4. The combination of claim 3 wherein: each element is a section of a hollow cylinder.
 5. The combination of claim 3 wherein: each element has a circular cross section.
 6. The combination of claim 2 further comprising: a gasket of resilient acoustic isolating material disposed between said tank and said radiating member.
 7. The combination of claim 2 further comprising: means for supporting said tank and oscillator combination, and acoustic isolators disposed between said radiating surface at the bottom of said tank and said support means.
 8. The combination of claim 7 wherein said support Means includes a resilient cushion spatially disposed from and surrounding a section of an outer wall portion of said tank.
 9. The combination of claim 1 further comprising: a mass attached to an end of the element opposite the end affixed to said radiating member. 